Telephone system



Jan. 3Q, 1934 H. M. FRIENDLY v 1,945,436

TELEPHONE SYSTEM Original Filed Sept. 23, 1921 9 Sheets-Sheet l 0 0 /OZ/0/ o Inveniur- ALjgs.

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mun N N Q NQ mm Jam 35 9 1934 Original Filed Sept. 25, 192-1 a z a z m Mw L 9% B wwv mmw RN Rm H h/ 5% m 3M EN EN hum NAN N z I 4 wk. TU nu m wA RN M a Patented Jan. 30, 1934 UNITED STATES PATENT OFFICE 1,945,468TELEPHONE SYSTEM Application September 23, 1921, Serial No. 502,626

Renewed April 9, 1926 127 Claims.

affording of operative conveniences to users and benefits to theoperating concern which have been heretofore unknown.

The invention in its specific form chosen for the illustration herein,contemplates a.so-called two-wire common battery automatic telephonesystem as has been widely used, the present invention necessitatingnovel departures from equipments heretofore known so far as I am aware,in attaining the new objects, while retaining certain operativefunctions which are known.

The exampled form of the present invention chosen to illustrate itcontemplates its adaptation to a comprehensive four-digit automatictelephone exchange system. However, the present invention is moreparticularly directed to that part of a comprehensive automatictelephone exchange system as relates to groups of subscriber's lines andto toll and special service.

In comprehensive automatic exchange systems there are various classes ofsubscribers, each demanding more or less special service and presentingvaried operating conditions. For example, certain subscribers generallytermed individual subscribers, have a single or isolated local line usedfor in-going and out going trafllc between the subscribers premises andthe main exchange. Other subscribers have a plurality of such lines,known as a group. Where a group of lines serves a subscriber it has beena practice heretofore to list one telephone number so that if thisnumber is called the group of lines will be reached and a first idle onethereof ,seized and rung upon, so thatthe operation so far as thecalling subscriber is concerned is the same when calling a subscriberhaving an individual line, or a group of lines serving his trafllc.

Where a group'of lines extend to the premises of a subscribertheyusually terminate in a private branch exchange switchboard, thecalls being answered by an attendant or operator, and then extended toany desired local telephone terminating in the private branch-exchangeswitchboard. Under this plan of operation, when the operator is absent,at night or on holidays, for example, it has been a practice to connectcertain ones of the lines of the group to certain local telephones sothat a call coming in over one of the thus connected lines of the groupwill signal the connected telephone directly, and may be answered byanyone near the concerned local telephone. Going further, it has been apractice to specially list certainptelephone numbers which are comprisedin the group, or which may not be comprised in the group but are incommon relation therewith in the main ofilce by reason of the bankcontacts corresponding to special non-group-selecting connectorbanknumbers listed being in multiple relation with the correspondingconnector bank contacts leading to the concerned line (or lines) of thegroup, so that as a matter of fact, the concerned line is reachable bycalling the regular listed telephone number accessible to agroup-selecting connector, or by calling a specially listed telephonenumber accessible to a non-group-selecting connector. The above practicerefers more particularly to private branch exchange subscribers havingone or more employes available at one or more specific telephones in theprivate branch exchange at nights and on holidays, for example and,therefore, affords a means of directing a call at these times to thespecial telephone.

Due to the inherent characteristics of the connectors heretofore knownso far as I am aware (such as connector C in Fig. 4 of my Patent No.1,506,054, granted Aug. 26, 1924) which automatically select a non-busyline of a group when the telephone number indicative of the entire groupis called, confusion is often entailed. For example, if the localtelephone connected to corresponding with the specially listed telephonenumber comprised in the group is busy, and therefore, the line of thegroup corresponding with the specially listed telephone number isguarded against intrusion, the group selecting connector concerned in acall transpiring will automatically select the first non-busy line ofthe group following. This will either signal a telephone not wanted onthe premises of the subscriber or it will seize a ,trunk line that hasno connected extension from the private branch exchange switchboard-and,therefore, will not be answered. Of course, where auxiliary or specialnumbers are assigned in non-group selecting connectors corresponding tospecific lines comprised in the groups as has been referred to,

specific line of the group is busy an alternative line of the group willbe selected unless, of course, the line is the last line of the group.The latter would only be possible where a single special number isconnected for night and holiday use.

a. The present invention contemplates, among other novel functions, and.the equipments for effecting them, a group-selecting connector which isnormally a non-group-selecting connector, but which is transformed intoa group-selecting connector, consequent to the first bank position of asubscribers group being encountered in a call from a subscriber'sstation, regardless of whether the line leading therefrom tests busy ornot.

From this it will appear that the connector of the present inventionreferred to will not rotate as a group-selecting connector if atelephone nber specific to a line of the group other than the lineoccupying the first bank position of the group is called. The presentinvention then, permits of any of the lines occupying bank positions ina group other than the first bank posi-= tion thereof being connected toa local telephone ina private branch exchange and insures that a calldirected to the listed telephone number corresponding to the specificline of the group will attain connection to the desired local telephoneor will give a busy signal to the calling party.

Auxiliary to inter-subscriber switching, comprehensive exchange systemsin nearly all cases contemplate the switching of toll lines to the locallines leading to the premises of subscribers. This switching is, innearly all cases, controlled or effected by an operator located at atoll switchboard situated within the confines of the exchange district,which shall betermed the exchange toll operator and the exchange tollswitchboard, respectively, or at some remote point wherein the switchingconnection is established by controlling automatic switching equipmentsover the toll line from which the connection to the subscriber isdesired.

b. Depending upon the traflic, various means for rendering this serviceto the subscribers have been employed. Where the traflic of a tollnature is very light and the local traflic is also light and not apt tointerfere seriously with the toll traflic, toll calls are routed overthe same lines from the main exchange to the premises of the subscriberas are used for local tramc, though it has been a practice to providespecific switching apparatus in the main exchange for attainingconnection to the local lines through convertible connectors in commonwith the, local apparatus directed by subscribers.

0. Another method which has been employed is that of providing anindependent line between a spring-jack on the exchange toll switchboardand the subscriber's premises reserved exclusively for toll service tothe subscriber and for the use of the subscriber in calling the exchangetoll operator. These shall be termed manual toll loops. The exchangetoll operator, under this method of operation, extends the call by meansof a switching cord-pair.

d. Another method which has been employed is that of providing anindependent line from a subscribers premises to a toll automaticswitching system, independent of the local automatic switching system,whereby the exchange toll operator can call over the independent line tothe subscriber automatically through a cordpair, through the agency of adial or other equivalent calling device. These shall be termed automatictoll loops". Systems 0! this kind have, in cases, been accessible notonly from the exchange toll switchboard located within the confines ofthe exchange district, but also accessible to toll operators at tollswitchboards located remotely, wherein the establishment of theconnection is controlled over the toll line from which the connection tothe subscriber is desired. The latter shall be termed the remote tolloperator and the'remote toll switchboard, respectively.

An undesirable feature involved in the methods set forth under paragraphc'f is that the exchange toll operator upon receiving the call for thesubscriber from a distant point must know ofbhand that the calledsubscriber has a special toll loop, so the call can be completed througha switching cord-pair. in view of the fact that in many cases calls aregiven by calling parties by number, and that it is quite impossible tomentally retain the information relating to all subscribers in largesystems and that it is not always convenient to consult an authenticspecial directory, the calls are very often routed over the regularexchange local lines to the subscribers, causing annoyance. Again, thesemanual toll loops not being accessible to operators located remotely,will mean that all remotely completed calls to a called subscriber overthe toll lines will reach the subscribers premises over the regularexchange local line and, as before stated, cause annoyance.

An undesirable feature involved in the method set forth under paragraphd is that the exchange toll operator on receiving a call from a distanttoll station for a local subscriber must know that the called subscriberhas a special automatic toll loop. Also, the remote toll operatorcalling for the subscriber automatically must know off-hand that thecalled subscriber has a special automatic toll loop, the same as wherethe toll loop terminates on a springjack on the exchange tollswitchboard reachable from the calling toll line through a switchingcord-pair. So it is necessary for the remote toll operator who may becalling over a toll line automatically, to have this information or itwill be completed under control of the remote toll operator over theregular exchange local line (or one of the exchange local lines) of thesubscriber, causing annoyance.

e. The present invention, wherein it relates to independent toll loops(manual and automatic) to the premises of local subscribers comprehendsmeans for automatically apprising the calling .toll operator (located inthe main exchange disthe group accessible to the group-selectingconnector used by the local subscribers in calling and also by the tolloperators, which shall be termed the exchange toll loop", but that thisexchange toll loop is only accessible to a toll operator calling throughthe special toll selectors, and is not accessible to a local subscribercalling through the local selectors.

j. A further function of the group-selecting connector referred to inparagraph c is that if the toll operator receives the tone indexing thatthe called subscriber has an exchange toll loop accessible through thegroup-selector connector then functioning, and also receives a' toneauxiliary thereto indicative that the exchange toll loop is busy, thetoll operator can, by sending digit 1, cause the group-selectingconnector to forthwith start functioning as a group-selecting connectorand seize the first disengaged local exchange line. If the exchange tollloop is not busy the connection can be completed normally, but theconnector will not function as a groupselecting connector, when reachedfrom a toll selector, unless the digit l is sent to initiate itsfunctioning as a group-selecting connector regardless of the busy oridle state of the exchange toll loop primarily called.

g. A further function of the group-selecting connector referred to inparagraph f is that should the toll operator call an intermediate lineof a group it will not function as a group-selecting connector unlessdigit 1 is sent to initiate such functioning, regardless of whether theintermediate line called is idle or busy.

h. A further function of the group-selecting connector referred to inparagraph 9, is that if the toll operator, upon calling an intermediateline of a group, receives a busy tone and the operator then sends thedigit "1, causing the connector to function as a group-selectingconnector, whereupon it seeks an idle line of the group of local lines,but fails to find a disengaged one, upon engaging the last tank positionof the group applies the customary busy-tone indicative that there areno idle lines in the group. The operator can, by sending an additionaldigit 1, cause the connector to be released to normal position. Theselector co-operating with the connector still maintains its seizure andthus enables a call to be completed through the connector to a line ofthe group last concerned, or to any other line accessible to theconnector, by calling two digits, whereupon the connector will functionas if it has primarily reached the last line called, and had not beenreleased. A further function of the group-selecting connector, effectivewhen it is co-Operated with a toll selector, is that when it is seizedby the cooperating toll selector, it applies a specific tone audible tothe calling toll operator indicative that the connector is seized, andmoreover, that it is at normal position, since the said tone isdisassociated consequent upon the first off-normal movement of theshaft.

2'. In view of paragraphs e and f it will appear that, if throughinadvertence, the toll operator ignores the fact that the called subscriber has a manual toll loop terminating in a springjack on theexchange toll switchboard, a specific tone will be applied audible tothe calling operator upon the connector attaining the called bankposition corresponding to the called line, regardless of its busy oridle state, prompting the fact there is such a toll loop, so theconnection can be taken down and properly routed.

a. It will appear that the present invention enables ihe toll operator,wherever located, to reach the called subscriber over his telephonenumber listed in the general subscribers directory and it will alsoappear that this exchange toll loop is barred against seizure by a localsubscriber calling the subscriber having the exchange toll loop, throughlocal selectors; such calls being directed to a local line of the group.

It. Another connector contemplated under the present invention is anon-group-selecting connector used for completing a connection to asubscriber's local line, that will function to pro- Ject a specific toneaudible to a calling toll operator indicative that the subscriber calledhas a manual toll loop terminating in a springjack on the exchange tollswitchboard, or has an automatic toll loop, perhaps, which can bereached through an auxiliary automatic toll exchange. The tone functionreferred to is dependent in a measure upon functions of the tollselector cooperating with the connector and, therefore, the said tonewill not be operative to local subscribers calling through localselectors to the connector.

Z. The shaft of the connector referred to in the last foregoingparagraph can be released to 'normal position under control of the tolloperator' if the line selected, called through a toll selector, testsbusy or the connector seizes. This releasing cannot be effected by alocal subscriber calling through a local selector. Of course, the tonethus appliedmay index any other condition relating to the calledsubscriber, such as to prompt the calling operator to refer to thecredit record, etc. In fact it is contemplated, as will appear, to havea plurality of tone sources interchangeably connected in relaiion to thesubscribers equipment so that various tones will be connectible toprompt any single one or a plurality of specific facts concerning thecalled subscriber, and other callable subscribers.

m. A function of the present invention relates to the toll loopsreferred to in paragraphs e" and I, wherein it the telephone terminatingthe exchange or automatic toll loop is removed from the switchhook whenthe line is normal in order to initiate a call to the toll switchboard,an outgoing call, for example, it will cause a local interofilce generaltraffic trunk to be seized and the call automatically directed andcompleted to the recording position of the exchange toll switchboard,without special operation on-the part of the calling subscriber. It willthus appear that where an exchange is made up of a plurality ofmain-branch offices the independent exchange and automatic toll loops ofsubscribers will be connec' ed into the same main-branch oflices as thelocal lines of the concerned subscribers.

Other novel functions and features, as well as the invention itself,will appear.

In the accompanying drawings:-

Fig. 1 shows an automatic telephone L leading into a lineswitch LS, andthe latter in 'ommon with other lineswitches (not shown) have access toa first selector FS. The first selector F8 in common with other firstselectors (not shown) have access to second selector SS. The secondselector SS, in common with other second selectors not shown) haveaccess to connectors A and F.

Fig. 2 shows a group-selecting connector A which has access tocooperating bank contacts.

Fig. 3 shows two local automatic subscribers lines and an exchange tollloop accessible to connector A.

Fig. 4 shows a toll selectorB which has access through cooperating bankcontacts with connectors A and F.

Fig. 5 shows an operators switching cord-pair C adapted to cooperatewith springjack D leading to toll first selector E. Selecor E in commonwith other first selectors similar to it (not shown) have access tosecond selector B.

Fig. 6 shows a non-group selecting connector F which has access throughcooperating bank contacts to two subscribers local lines.

Fig. '7 shows a normal-level selector I terminating an inter-oflicetrunk. Through its normal level it has access to equipments H located ona recording position of the exchange toll switchboard. Through its firstlevel, and other levels not shown, calls can be forwarded in thedirection of called local subscribers lines.

Fig. 7A shows a novel mechanical detail 01' two companion relays in Fig.7 wherein one of the relays is shown operated, restraining the other.

Fig. 8 shows a schematic arrangement of two banks of contacts, such asare shown cooperating with connector A of Fig. 2, but in more detail.The bank contacts designated J correspond to the bank contacts showncooperating with the said connector A, while the banks designated Krepresent one of a plurality of banks which cooperate with connectorssimilar to said A of the connector group. It will thus be clear that thebank contacts shown in the bank cooperating with said A are in multiplerelation respectively with the contacts of banks cooperating with aplurality of respective connectors similar to said A of the group. Theconductors leading from the respective multiplied contacts located incor= responding relation to the respective connectors 25 of the grouplead to terminals from which the connections contemplated under thepresent in-= vention can be made and altered from time to timewithout-consideration of each bank individually.

Fig. 9 shows a toll line leading from a springjack L on the exchangetoll switchboard to a remote toll station telephone T9.

Fig. 10 shows a manual toll loop leading from a springjack M on theexchange toll switchboard to a subscriber's toll telephone T10.

Fig. 11 shows the arrangement of the figures concerned in a call fromthe exchange toll switchboard to toll loop telephone T23 or to localtelephones L12 and L24.

Fig. 12 shows the arrangement of the figures concerned in a call fromlocal telephone L to local telephones L12 -or L24.

Fig. 13 shows the arrangement of figures concerned in a call from localtelephone L to local telephones L6 or L6.

Fig. 14 shows the arrangement of the figures concerned in a call fromtoll loop telephone T23 to the exchange toll switchboard.

Fig. 15 shows the arrangement of the figures concerned in a call fromthe toll switchboard to local telephones L6 or L6.

Fig. 16 shows the relative location of the sets of bank contacts in thebank cooperative with connector A with respect to the bank positionsthereof.

Referring to certain of the various figures:

In Fig. 1, L is a usual series type of automatic telephone having acalling device 102 of the general class as shown in British patent toDicker No. 29,654 of 1910. The lineswitch LS is of the general class asshown in U. S. patent to Lamb, No. 1,193,160, granted August 1, 1916.The first selector FS is of the general class as shown in U. S. patentto Keith and Erickson, No. 815,321, granted March 13, 1906, of course,modified in mechanical and circuit details to operate on the well knownso-called two-wire principle and in accordance with the presentinvention. The second selector SS is similar in detail to first selectorFS. In this connection it-may be stated that tele-- phone L, lineswitchLS, first selector FS and second selector SS, may for the purposes ofelucidating the present invention, be considered as telephone A,lmeswitch C, first selector E andv Frank Newforth, April 13, 1915,numbered 13,901.

In Fig. 2 the novel group-selecting combination local and toll connectorA is 01 the general class as shown in U. S. patent to Keith andErickson, No. 815,176, granted March 13, 1906, or course, modified inmechanical and circuit details to operate on the well known so-calledtwo-wire principle and in accordance with the present invention.

In Fig. 3 telephones L12, L24, T23 and E3 may be considered similar indetail to telephone L. Lineswitch LS3 may be considered generallysimilar to LS. Relays 301 and 302 may be considered as representinglineswitches similar to LS. Lineswitch LS3 may be considered similar indetail to iineswitch LS. First selector PS3 may be considered similar indetail to selector SS.,

Repeater R3 is a novel device for localizing the battery supply to acalling telephone and for repeating impulses to switches interlinked inthe direction of the called line.

In Fig. 4. the novel. toll selector B, adapted for cooperating withcombination local and toll connectors A and F, belongs to the generalclass to which selector FS belongs.

In Fig. 5 the toll first selector E belongs to the general class towhich selector FS belongs, and is well known in the art.

In Fig. 6 the novel non-group selecting combination local and tollconnector F belongs to the general class to which connector A belongs.Telephones L6 and L6 may be assumed similar in detail to telephone L.

In Fig. 7 the novel normal-levelselector I belongs to the general classto which selector FS belongs. Connector CS7 may be assumed similar indetailto connector F. lelephone L? may be assumed similar in detail totelephone L. Relay 700 may be assumed to represent a lineswitch similarin detail to 18.

In Fig. 9 telephone T9 is a well known type of bridging local batterytelephone.

In Fig. 10 telephone T10 is a well known type 01' non-automatic localbattery telephone.

To simplify the drawings and descriptions, battery and ground are shownas independent sources throughout, wherever applied, but it is to beunderstood that the system is of the common battery type. In thedescriptions, when a circuit is traced to a winding, the oppositeterminal of which is shown applied .to grounded battery or to ground,the described circuit is to be considered as traced to ground throughthe winding to bats tery, or direct to ground as indicated.

The performance of the equipments will be detailed under differentassumed operative conditions, having in mind that the equipment elementsmay be, and in fact, ordinarily would be variously organized in theassembly of a system.

Referring to the accompanying drawings:-

With reference to Fig. 13, it will be assumed that a call from telephoneL is to be extended to called telephone L6, the telephone number 01which is 1212". Upon the calling subscriber. re-

'moving the receiver from the switch-hook of telephone L, lineswitch LSwill automatically seize a trunk to a disengaged first selector FS. Uponsending the first digit 1 by manipulating the calling device 102 inaccordance therewith, selector FS will step its wipers into alignmentwith the first level of its bank contacts and automatically rotate-inand seize a trunk leading to an idle second selector SS. Upon sendingthe second digit 2".selector SS will step its wipers second selector Fshown in the patent reissued to into alignment with the second level ofits bank "wherein the receiver at telephone L6 is removed contacts andautomatically rotate-in and seize a trunk leading to an idle connectorF.

A circuit can now be traced from the upper winding of relay 601,make-beiore-break spring 602, conductor 603, wiper 101, conductor 102,wiper 103, conductor 104, wiper 105, conductor 106, through receiver oftelephone L, conductor 107, wiper 108, conductor 109, wiper 110,conductor 111, wiper 112, conductor 113, make-before-break spring 604 tothe lower winding of relay 601, relay 601 actuating. A circuit can nowbe traced from the winding of slow-releasing relay 606 to groundedarmature 607, relay 606 actuating. Grounded armature 608 applies itsground to conductor 609, wiper 114, conductor 115, wiper 116, conductor117, wiper 118 to the winding of cut-off relay 119 of lineswitch LS,maintaining the said lineswitch in the well known manner.

Upon the calling subscriber sending the third digit 1, relay 601 willde-actuate and re-actuate one time. Ground from armature 607 will beapplied to armature 612, armature 613, series winding of slow-releasingrelay 614, winding of vertical magnet V6, sideswitch wiper 615 togrounded battery, causing relay 614 to actuate, and to operate thevertical magnet one time to step the shaft carrying wipers 616 to 619(inclusive) into alignment with its first bank level. Incidental to theoperation of relay 614, grounded armature 620 engages make-before-breakspring 621 and applies ground to the winding of private magnet P6,energizing it preparatory to permitting the sideswitch wipers 615 and622 to advance into their second position. Upon relay 614 deactuatingits period after the opening of the energizing circuit including thewinding of vertical magnet V6, the sideswitch wipers 615 and 622 willadvance-into their second position.

Upon the calling subscriber sending the fourth digit 2, relay 601 willdeactuate and re-actuate' two times. Armature 607 will apply its groundtwo times over a circuit including armature 612, armature 613, windingof relay 614, armature 624, winding of rotary magnet R6, sideswitchwiper 615 to grounded battery, causing relay 614 to actuate and operatethe rotary magnet two times to step the wipers 616 to 619 intoengagement with bank contacts 625 to'628 respectively. Upon relay 614de-actuating its period after the opening of the energizing circuitincluding the winding of rotary magnet R6, the sideswitch wipers 615 and622 will advance into their third position. A circuit can now be tracedfrom ground, sideswitch wiper 622, winding of relay 629, sideswitchwiper 615 to grounded battery, relay 629 actuating. A circuit can alsobe traced from ground sideswitch wiper 622, wiper 617, bank contact 626to the winding of cut-ofi relay 630 of the lineswitch similar to LSassociated with the line leading to L6, disassociating it from thetelephonic conductors of the said line in the well known manner.

A circuit can now be traced from grounded interrupted ringing currentsource G6, armature 631, armature 632, armature 633, armature 634, wiper619, bank contact 628, signal bell at telephone L6, bank contact 627,wiper 618, armature 635, armature 636, armature 637, armature 638, innerwinding of relay 640 to grounded battery. The signal bell 641 oftelephone L6 which includes condenser 642 will be operated, but thecharacteristic of relay 640 is such that it will notice operativelyenergized by the said ringing current. However, upon the response of thecalled party,

from the switchhook, aconductive circuit can be traced from groundedringing current source G6 over the traced path, now including thereceiver or telephone L6. Relay 640 will operate. A locking circuit forrelay 640 can now be traced from its outer winding, armature 643,conductor 644 to grounded oft-normal spring 645. Off-normal spring set0N6 is adjusted to closeits contacts upon the first oil-normal movement01 the shaft carrying wipers 616 to 619.

A circuit can now be traced from upper winding oi. relay 646, conductor647, armature :636,

telephone L6, armature 633, conductor 648, lower winding of relay 646,armature 643, conductor 644 to grounded spring 645, relay 646 actuating.Incidental to relay 646 actuating its armatures 649 and 650 engagemake-before-break springs 602 and 604 respectively, and therebyreciprocate therelationship oi the windings of relay 601 to conductors603 and 113 as primarily existing. A telephonic circuit now exists fromthe calling telephone L to conductors 603 and 113 and from conductor603, condenser 651, conductor 647 over the traced circuit including thereceiver of telephone L6 to conductor 648, condenser 652, to conductor113.

Assume that the called party at telephoneL6 restores the receiver at thetermination of the conversation, the calling subscriber still holdingthe receiver 011' the switchhook. Relay 646 will deactuate, restoringthe direction of current traversing the receiver oi. telephone L to thatprimarily existing. Upon the calling subscriber now replacing thereceiver on the switchhook opening the energizing circuit of relay 601,and its dependent relay 606, a circuit can be traced from the winding ofrelease-magnet Re6, armature 655, spring 656 to grounded armature 608,the release magnet operating to restore the shaft .-carrying wipers 616to 619 to normal position.

Ground being removed from conductor 609 consequent to armature 608retracting, lineswitch LS, first selector FS and second selector "SSwill 11 restore in the well known manner, whereupon the concernedcircuits and. equipments are at normal.

It, at the time wiper 617 engaged bank contact 626 it found groundpotential thereon, due to a connector having access ,to a multipledcontact 134 thereof being in seized engagement with it, ap-- plying aground to it as was set forth in relation to connector F hereinbefore, acircuit would ,have been established from grounded contact 626, wiper617, wiper 622, winding of relay 657, make- 13 before-break spring 621to the winding of private magnet P6, thus maintaining the privatemagnet, notwithstanding the retraction of armature 620. Under thiscondition sideswitch wipers 615 and 622 are not permitted to advanceinto their third position, so that relay 629 will not actuate.Consequent to the actuation of relay 657, grounded tone source T6 isapplied through-armature 659 to conductor 648 and over the describedpath including the receiver of telephone L, conductor 603, upper windingof relay 601 to grounded battery, the tone being audible to the callingsubscriber indicative that the line leading to telephone L6 is busy. Alocking circuit for relay 657 is established incidental to its actuationfrom the winding of private magnet P6, spring 621, winding of ,relay657, armature 660, armature 661, conductor 644, to grounded spring 645.The tone, and the private magnet is thus maintained until the lockingcircuit is opened at spring 645, which no can only occur when the switchhas been restored to normal by the calling subscriber replacing thereceiver on the switchhook, as described.

Inasmuch as features of novelty in connector F residein the convertingrelay 662 and in bank contact 625, wiper 616, and the circuitsinterlinked therewith, and that these have not been brought intorequisition in the described call from telephone L to telephone L6, thefunctioning of the equipments concerned has been substantially as inwell known types of equipments. However, it will appear presently, theconnector F operates in a novel manner under certain operativeconditionswhich relate to calls efiected wherein a toll selector B cooperates withit, in lieu of a local selector SS as has been described.

With reference to Fig. 15 it will now be seen how a call is extendedthrough the toll switchboard springjack D to called telephone L6. Uponinserting switching plug 501 of switching cordpair G into springjack Dleading over a trunk to toll first selector E, spring 502 applies itsground to conductor 503. In this connection it will be stated thatconductors 503 to 506 are in multiple relation to other springjackssimilar to D and that there are lamps connected correspondingly to 507associated with each said springjack so that when the multipled lampscorresponding to 507 glow due to conductor 503 becoming groundedoperators will know that the first selector E is busy by having beenseized by some operator having access to it. A circuit can now be tracedfrom the winding of marginal relay 508, makebefore-break spring 509 ofcalling device key d, sleeve conductor 510, conductor 512, spring 513,conductor 504, armature 514 to the winding of relay 515, relay 515actuating. A circuit can now be traced from grounded armature 516 to thewinding of slow releasing relay 517, relay 517 actuating. .Groundedarmature 518 places a supplemental ground on conductor 503.

The operator will now manipulate calling device key d, whereupon acircuit can be traced from ground through the calling device 520 (whichis similar to the calling device in tele= phone L), spring 521, spring509, conductor 510, conductor 512, spring 513, armature 514 to thewinding of relay 515. Upon the operator manipulating the calling device520 in accordance with the first digit 1, relay 515 will de-actuate andreactuate one time responsive thereto, whereupon armature 516 closes acircuit from its ground, armature 523, series winding of slow-releasingrelay 524, armature 525 to the winding of the vertical magnet V5, thevertical magnet operating one time resultant thereto and raises theshaftcarrying wipers 526 to 529 one vertical step into alignment with itsfirst bank level.

At the time relay 524 actuates, coincident with the energization of thevertical magnet V5, its armature 533 applies ground from conductor 503to make-before-break spring 534, winding of relay 535, armature 536, onthe rotary magnet R5 to grounded battery, relay 535 actuating and closesa locking circuit from its upper winding terminal, spring 537 ofoff-normal set 0N5, conductor 538, armature 539, to grounded conductor503. Oil-normal set 0N5 operates upon the first ofi-normal movement ofthe shaft. Upon the retraction of armature 533 a circuit can be tracedfrom the winding of rotary magnet R5, spring 534, spring 537, conductor538, armature 539 to grounded conductor 503, the rotary magnet operatingand advances wipers 526 to 529 into engagement with bank contacts 541 to54% respectively acumen and incidentally disconnects the batteryenergizing relay 535 at armature 536, relay 535 deactu ating. armature536 retracts after the described energizing circuit of the rotary magnetis opened at armature 539 a circuit can be traced from grounded batteryarmature 536, winding of relay 535, spring 537, conductor 538, windingof relay 546 to grounded conductor 503, relay 546 actuating. Themarginal adjustment of relay 535 is such that it will not operativelyenergize with the winding of relay 546 included with its winding. Relay546 being actuated, the winding of relay 515 is disassociated and itretracts, followed by the de-actuation of relay 517 in sequence.

A circuit can now be traced from conductor 504, armature 514, wiper 527,bank contact 542, conductor 400, armature 401 to thewinding of relay402, relay 402 actuating. Upon relay 402 actuating, a circuit can betraced from the winding of slow-releasing relay 403 to grounded armature404, relay 403 actuating. Armature 405 engages grounded contact 406 andgrounds conductor 407 which is communicated to bank contact 541, wiper526, armature 550 to conductor 503, supplementing the ground thereonreceived from the spring 502. The telephonic circuit extends from thetip spring 551 of spring-jack D, conductor 505, armature 552, wiper 529,bank contact 544, conductor 553 to winding 408 of repeating coil 1', andfrom the ring spring 554, conductor 506, armature 555, wiper 528, bankcontact 543,

conductor 556 to winding 409 of repeating coil 1'.

Having in mind that the bank contacts in cooperative relation withselector E are in multiple relation with corresponding bank contacts incooperative relation with other selectors belonging to the groupcontaining E, and the-fact that when armature 550 attracts it appliesground from conductor 503 to wiper 526 and to bank contact 541 and itsmultiples that had the selector B been in a seized condition before thedescribed operation ensued relating to switch E in seizing it, bankcontact 541 would have constituted ground potential. Therefore, whenwiper 526 encountered bank contact 541 and received ground potentialtherefrom, it would have applied it to the lower winding terminal ofrelay 546 in common with the ground received from conductor 503 by wayof armature 539. Relay 546 having ground on both of its windingterminals cannot be energized, so when armature 536 retracts followingthe driving of wipers 526 to 529 into engagement with bank contacts 541to 544 respectively, an

energizing circuit operative to relay 535 will be established fromgrounded battery, armature 536, winding of relay 535, spring 537 togrounded conductor 538. Armature 539 will again lock the winding ofrelay 535 to grounded conductor 503 and the rotary magnet R5 will beoperatively reenergized over the before described path to conductor 503and an auxiliary path from conductor- 538, armature 550, wiper 526 togrounded bank contact 541 which will cause the rotary magnet to advancethe wipers 526 to 529 an additional step into engagement with bankcontacts 558 to 561 respectively, the re-actuation of relay 535 and there-functioning of the rotary magnet occurring to advance the wiperssuccessive rotary steps as long as wiper 526 receives ground to reestablish the energizing circuit of relay 535 following itsde-energization incidental to the rotary magnet operating.

Continuing from the seizure of selector B by selector E as set forth,upon the operator sending Armature 539 being now retracted, when I thesecond digit 2" relay 402 will de-actuate and re-actuate two timesresponsive thereto, whereupon armature 412 closes a circuit from itsground, armature 413, armature 414, winding of series slow-releasingrelay 415 to the winding of the vertical magnet, V4, the vertical magnetoperating two times resultant thereto and raises the shaft carryingwipers 416 to 419, 479 and 483 two vertical steps in alignment with itssecond bank level. At the time relay 415 actuates,'coincident with theenergization of the vertical magnet V4, its armature 420 applies groundfrom conductor 407 to conductor 421, spring 422 of off-normal set 0N4 tothe shunted winding of relay 425, relay 425 actuating. Off-normal set0N4 operates upon the first elf-normal movement of the shaft. A lockingcircuit for relay 425 is established from grounded armature 426,armature 427 on rotary magnet R4, conductor 421, spring 422, to thewinding of relay 425. Upon the retraction of armature 420 a circuit canbe traced from the winding of the rotary magnet R4, armature 428,armature 420 to grounded conductor 407, the rotary magnet operating andadvances wipers 416 to 419, 4'79 and 483 into engagemen'; with bankcontacts 430 to 433, 493 and 494, respectively. Upon armature 427retracting a circuit can be traced from the winding of relay 425, spring422, conductor 421, armature 427, conduclor 445, winding of relay 446 togrounded conductor 407, relay 446 actuating. Relay 425 is marginallyadjusted to not operatively energize over a circuit including thewinding of relay 446.

Had wiper 418 encountered ground potential on bank contact 432, groundpoiential received therefrom would be conducted over wiper 418, armature447,conductor 450,armature 451 to conductor 445, thus maintaining groundpotential on both winding terminals of relay 446, and a ground path fromthe winding of relay 425, spring 422, conductor 421, armature 427 to theground on conductor 445, operatively energizing relay 425, whereupon therotary magnet R4 will be caused to operate as before and advance thewipers an additional rotary step; this functioning continuing untilwiper 418 fails to receive ground potential from an engaged bankcontact.

Having in mind that the bank contacts in cooperative relation withselector B are in multiple relation with corresponding bank contacts inco-operative relation with other selectors belonging to the groupcontaining selector B, it will presently appear that the assumed groundon bank contact 432 would occur whenever a selector belonging to thegroup containing selector B is in seized relation to its co-operativeset of bank contacts.

consequent to the actuation of relay 446 set forth a circuit isestablished from grounded armature 412, armature 453, conductor 454,wiper 416, bank contact 430, conductor 455, makebefore-break spring 602to the upper winding of relay 601, no circuit being traceable from thelower winding of relay 601. However, relay'601 is operatively energizedover the traced path. Upon the actuation of relay 601 the hereinbeforedescribed actuation of relay 606 ensues, applying ground from armature608 to conductor 609. A circuit can also be traced from groundedbattery, resistance 456, armature 451, conductor 450, armature 447,wiper 418, bank contact 432, conductor 457, winding of relay 662 togrounded conductor 609, relay 662 actuating. At this juncture relay 546in selector E, relays 446, 402 and 403 of selector B and relays 601, 606and 662 of connector F are actuated.

Upon the operator sending the third digit 1, I

relay 601 will be caused to de-actuate and reactuate one time and causethe connector F to function as hereinbefore described to step itsvwipers 616 to 619 into alignment with its first bank level. Upon theoperator sending the fourth digit 2, relay 601 will be caused todeactuate and re-actuate two times and cause the connector F to functionas hereinbefore described and to step its wipers 616 to'619 intoengagement with bank contacts 625 to 628-respectively.

It is assumed that the subscriber upon whose premises telephone L6 islocated also 'has a manual toll loop, such as is shown in Fig. 10,extending from a springjack M on the exchange toll switch-board to anindependent telephone T10 on the premises of the said subscriber. Itwill be further assumed that the toll operator inadvertently orunknowingly called the subscriber's said local number to complete thetoll call in place of properly routing it over the said toll loop. Uponthe wipers 616 to 619 engaging bank contacts 625 to 628 respectivelygrounded special tone source S6 will be applied from bank contact 625,wiper 616, armature 665, conductor 666, bank contact 431, wiper 417,armature 460, winding 409 of repeating coil 1', conductor 556, over thedescribed path to spring 554 of springjackD, conductor 565 of plug 501,spring 566 of key e, spring 567 of listening key 9 (now operated)through operator circuit N5, spring 568, spring 569, conductor 570,spring 551 over the described path to winding 408- of the repeating coil1', armature 463, resistance 464 to ground, the said tone being audibleto the calling toll operator, and due to its distinctiveness, isindicative that the subscriber called has a manual toll loop as setforth. In this connection, it will be observed that due to the fact thatrelay 662 is attracted incidental to the connector F being seized byselector B, that the before traced path from grounded ringing currentsource G6 is open at armature 632, and therefore, under the condition ofthe connector F being seized by toll selector B the automaticapplication of ringing current to a seized subscriber's line will notensue. Under the condition of receiving the stated tone the tolloperator may withdraw the plug 501 preparatory to inserting it intospringjack M and thereafter depressing the ringing key e and apply theringing current source G5 in bridge of springs 52 and 53 of springjack Mleading to telephone T10 and operate the bridged signal device 54thereat.

Assuming first that the operator withdraws the plug as referred to inthe foregoing paragraph, ground on spring 502 will be removed fromconductor 503, however, to no operative result because of conductor 503receiving the stated supplemental ground by way of armature 405 inselector B. However, spring 513 will open the traced energizing circuitof relay 402, causing it to deactuate and, in turn, open the tracedenergizing circuit of relay 601, causing it to deactuate. The retractionof relay 601 will cause the connector F to be released as hereinbeforedescribed with relation to the call from telephone L to telephone L6.The retraction of relay 402 followed by relay 403 in sequence, willestablish an operative circuit from grounded armature 412, armature 413,

IOU

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armature 414, spring 465 to the release magnet the traced energizingcircuit for relay 546 will be opened, whereupon relay 546 willde-actuate, establishing an operative circuit from grounded armature516, armature 523, winding of relay 524, armature 525, spring 575 to thewinding of release magnet Re5, causing selector E to restore its shaftto normal position, whereupon the concerned circuits and equipments areat normal.

Assume now that for some reason,perhaps that the manual toll loopextending to the premises of the called subscriber is busy and the tolloperator, therefore, wishes to complete the connection over the seizedlocal line to telephone L6 in lieu of releasing the connection. The linehaving been seized, but not rung upon, the operator will depress ringingkey e and apply ringing current source G5 in bridge of the tracedcircuit leading to the lower winding 408 and the upper winding 409 ofrepeating coil 1'. The inner terminals of the windings 408 and 409 areopen at armature 460, but the relay 466 including condenser 467 isincluded in a bridged circuit from the outer terminal of the winding 409by way of armature 468 to the outer terminal of winding 408, therefore,in a bridge of conductors 556 and 553. Relay 466 is operative to theimpressed ringing current from source G5 and attracts its armature 470into engagement with its co-operating grounded contact, applying theground to the winding of slowreleasing relay 471, causing it to actuate.Armature 447 attracting (after armature 472 attracts), opens the tracedenergizing circuit of relay 662, whereupon said 662 deactuates. Armature472 attracting into engagement with its co-operating grounded contactapplies ground through wiper 419, bank contact 443, conductor 473 to thewinding of relay 675, causing it to actuate. A circuit can now be tracedfrom grounded ringing current source GT6, armature 631, armature 632,armature 633, armature 634, wiper 619, bank contact 628, condenser 642,signal bell 641, bank contact 627, wiper 618, armature 635, armature636, armature 637, armature 638, resistance 676 to grounded battery, thesignal bell 641 operating. Upon the operator restoring the key e relay466 will retract, opening the traced energizing circuit of relay 471,causing relay 662 to re-actuate, followed by relay 675' de-actuating incorrespondence with the stated relative adjustments of armatures 447 and472.

Upon the called subscriber responding, by removing the receiver oftelephone L6, a circuit can be traced from the upper winding of relay475, armature 476, winding 477 of repeating coil 1', conductor 478,wiper 479, bank contact 480, conductor 481, armature 637, armature 636,armature 635, wiper 618, bank contact 627, receiver of telephone L6,bank contact 628, wiper 619, armature 634, ,armature 633, armature 632,conductor 678, bank contact 482, wiper 483, conductor 484, winding 485of repeating coil 1', armature 486, to the lower winding of relay 475,relay 475 actuating. consequent to relay 475 actuating the traced pathincluding relay 466 is opened. Relay 402 is dis-associated and armature488 applies ground from its co-operating grounded contact througharmature 453, conductor 454, wiper 416, bank contact 430, conductor 455,spring 602 to the upper winding of relay 601, maintaining relay 601actuated. Armature 401 is applied to its working contact and, therefore,applies conductor 400 to the winding of relay 403 in lieu of to thewinding of relay 402 normally existing. The winding of relay 402 hassuch a resistance as will permit current sufficient to operativelyenergize the includ ed winding'of relay 508 to flow, and, therefore,

de-energizing relay 475, the primary circuit relations will re-exist andrelay 508 will be again operatively energized in series with the windingof relay 402, whereupon lamp 570 will re-glow as a clearing signal.

The telephonic circuit previously traced to the inside terminals of thewindings 408 and 409 of repeating coil r is closed through armature 460.The telephonic circuit traced through the called telephone to the innerterminals of windings 477 and 485 of repeating coil 1'; the said innerterminals being connected by condenser 489, and in view of the windings409 and408 being in inductive. relation to companion windings 477 and485 respectively, the toll operator, through the operator circuit N5, isin telephonic relation with the called subscriber through the receiverof telephone L6. It is manifest that upon the armatures 460 and 463attracting, the special tone derived from tone source S6 isdisassociated from the telephonic conductors.

Assume that telephone L6 had been called by sending digits correspondingto telephone number 1211 wherein the last digit 1 will cause wipers 616to 619 to engage bank contacts 681 to 684 respectively and wherein thetelephonic circuit traced to wipers 618 and 619 will include a paththrough the telephone L6 in a manner corresponding to the inclusion oftelephone L6 when engaged with bank contacts 627 and 628 respectively.Wiper 617 will apply ground. to the winding of cut-off relay 685 throughbank con- The tone projected from tone source U6 differs j from thatprojected from tone source $6, the

tones being distinctive so as to prompt the toll operator of specificconditions with reference to the respective subscribers L6 and L6. Forexample, in the case of tone source U6 it may be 3 indicative that thesubscriber is not to be accorded credit, and therefore, no collect tollmessage shall be completed. It would be equally practicable to have thetone from the source U6 indicative that the subscriber can be reached jthrough an independent toll automatic exchange over an automatic tollloop, or in fact any of many special facts relative to the subscriber.-It is manifest that there may be a greater plurality than the two tonesources (S6 and U6) available for interchangeable connection to bankcontacts.

engageable to wiper 616, each indicative of a specific condition orconditions relative to the subscriber.

Assume that at the time the wipers 616 to 619 inbefore set forth, thatthe line leading to tele- 1' phone L6 is busy. A circuit can be tracedas before from grounded contact 626, wiper 617, sideswitch wiper 622,winding of relay 657, spring 621 to the winding of the private magnetP6, relay 657 actuating, and it and the private magnet being maintainedafter the retraction of armature 620. Tone source T6 is applied througharmature 659, resistance 685', conductor 6'78, bank contact 482, wiper483, conductor 484, winding 485 of repeating coil 1', armature 486 tothe lower winding of relay 475. The tone will be induced into winding408 audible to the toll operator calling, indicative that the calledline is busy. Due to armature 661 being attracted, the locking circuithereinbefore traced to the winding of relay 657 will not be completed,and therefore, the attraction of relay 657 will only endure as long aswiper 617 receives ground from bank contact 626; that is to say, untilthe line leading to the telephone L6 becomes disengaged. Under thiscondition, the operator can hold the connection awaiting thedisengagement of the called line, whereupon the connector F will seizeas before described, due to the fact that when the ground is removedfrom bank contact 626 the private magnet P6 is deenergized, permittingthe sideswitch wipers 615 and 622 to advance into their third position,energizing relay 629 and applying busy ground to bank contact 626 andits multiples.

It is manifest that upon receiving the busy tone last assumed that twoindependent tones will be audible to the calling toll operator. One tonebeing that derived from tone source S6 and the other being that derivedfrom busy tone source T6. In order for these tones not to be confusing,they are not applied constantly and are so timed in their propagationand duration that they are alternately audible. This expedient isattained through timing the interrupter control segments as by givingthem suitable angular position with respect to each other on the shaftdriving them. The same method of alternatively applying tone sourceswhich may be successively applied audible to the calling toll operatorto index a plurality of specific conditions relative to a subscriber iscontemplated under the present invention. For example, the tone appliedto a bank contact engageable to wiper 616 may constitute a cycle oftones consisting of a plurality of specific tones, each indicative of aspecial condition, as that the subscriber called has an automatic tollloop, a manual toll loop, that collect calls are to be completed onlyupon the subscriber personally recognizing the charge, that if noresponse is obtained instructions are on file which the operator shallconsult as to where the call can be completed,

etc.

In view of the foregoing, with relation to the application of tones, itwill be understood that the various tone sources of the exchange are so.timed and durated that tone sources which may be successively appliedwill not be operative during the same period, that is, there will beaudible and silent periods for the various tones and the said periodsintermesh when considered in plurality. It will thus be clearlyunderstood that the toll operator may receive a composite tone, possiblyapplied from a single composite tone source of predetermined character,which will indicate a plurality of facts relative to the subscribercalled.

In carrying out the present invention in commercial exchange systems itis not always practicable to install a manual toll loop from thepremises of the subscribers to the exchange toll switchboard, nor wouldindependent automatic toll switching equipments be installed to whichautomatic toll loops could'be connected. This is having in mind that thesubscribers lines lead into various main branch oflices of the exchange,all of which may be remote from the exchange toll switchboard, or fromthe terminating first selector (corresponding to E) of a toll lineequipped for automatic calling.

It is manifest that it is practicable to reserve certain numbers in eachhundred-group bank accessible to the connectors, as F, to which exchangetoll loops can terminate in a manner corresponding to L6 or L6. That is,for example, the telephone line leading to telephone T23, may have itstelephonic conductors and private normal conductor related to bankterminals accessible to connector F corresponding to the relation of thetelephonic conductors and the private normal conductor of the lineleading to telephone T6. So, in view of the descriptions relating to theequipments of the line extending to telephone T23 which will be detailedpresently, it will be clear that exchange toll loops may be terminatedin the same hundred groups as the local exchange lines of thesubscribers concerned- Having the exchange toll loops in the samehundred group is particularly advantageous in view of the novel releasefunction of connector F under control of a toll operator when it isseized by a t )11 selector B, about to be described.

It will be assumed that upon the toll operator (exchange or remote)attaining the bank position containing bank terminals 681 to 684corresponding to the line leading to telephone L6 atom is receivedindicative that the concerned subscriber has an exchange toll loop inthe same bank group, and tone is received indicative of the calledlinebeing busy. The toll operator will consult the toll loop directory andascertain the bank position (corresponding to the last two digits of thetelephone number) of the said exchange toll loop. That is-to say, thetelephone number of the said loop.

In order to effect connection with the desired exchange toll loop theoperator will send digit 1, whereupon relay 601 will de-actuate andreactuate one time responsive thereto. Upon armature 607 retracting itwill apply its ground through armature 612, conductor 687, armature 688on relay 657 which is actuated due to the -busy condition found,armature 689 on converting relay 662, to the winding of the releasemagnet Re6, the said release magnet actuating to restore the shaft ofconnector F to normal position, toll selector B retaining its seizurethereof. The toll operator can now send the last two digits of .thetelephone number corresponding to the exchange toll loop extending totelephone T23 and cause the connector F to attain its bank position,whereupon it will seize its contacts if the said loop is idle, or applya tone audible to the calling operator indicative thereof if it is busy,in the manner hereinbefore set forth when the line leading to telephoneL6 was assumed busy.

Assume that the line leading to telephone L6 does not test busy whenwipers 616 to 619 attain engagement with bank contact 681 to 684respectively, and therefore relay 657 will not actuate, but that cut-onrelay 629 will actuate to effect a seizure, instead. The callingoperator discerning the tone indicative of the fact that the calledsubscriber has an exchange toll loop in the same bank group will refrainfrom applying signaling 159 current. Upon sending digit "1", whereuponrelay 601 will de-actuate and re-actuate one time and armature 607 willapply its ground through armature 612, conductor 687, armature 613, (inlieu of 688 in the before traced path) armature 689 to the of therelease magnet Red, the said release magnet actuating to restore theshaft of connector F to normal position, the toll selector B retahzingits seizure thereof. The toll operator can now send the last two digitsof the telephone number corresponding to the exchange toll loopextending to telephone T23 and cause wipers of the connector F to attainits bank position, whereupon it will function in accordance with itsbusy or idle condition as set forth hereinbefore.

It is thus manifest that if the connector F attains a bank position,controlled by a toll operator through a toll selector B, and it thereencounters either a busy line from which it is barred, or an idle linewhich it seizes, dialing digit 1 will restore the connector and maintainthe interlinked circuits up to and including the said connector,preparatory to operating the connector as primarily.

It is clear that wipers 616 and 617 may be tied, and the engageablepairs of bank contacts thereof may be tied, without operative change.That is to say, the conductor leading to wiper 616 may be changed towiper 617 and the tone connections to bank contacts 681 and 625 may bechanged to bank contacts 682 and 626 respectively.

With reference to Figs. 8, 12, and 16, and also with referencetoparagraphs, a, b, c, d, e, f, g, h, i and 7', the'operation ofconnector A under various assumed operative conditions will bediscussed.

In order not to unduly complicate the drawings, only a portion of theconnections are shown relating to the bank contacts co-operating withconnector A. Bank J shown in Fig. 8 is a somewhat more completerepresentation of the bank co-operating with the connector A and itshows one of the multiplied banks K co-operating with a connector of thegroup containing connector A. Only the first and second bank levels areshown, and only six sets of contacts are shown for each level. Incommercial systems the bank would consist, ordinarily, of ten levels often sets of bank contacts each and would, therefore normally refer to ahundred lines or a hundred bank positions. Usually ten or more banks areconnected in a set with their contacts connected in multiple relationrespectively, so that the cooperating connectors each have access to thesame leading-out lines at corresponding bank positions.

The connector A is a combination local and toll group-selectingconnector which is normally not a group selecting-connector. Thegroup-selecting function depends upon a set-up condition beingintroduced, depending upon the condition found by one of its wipers whenit engages the co-operating bank contact of the bank position called. Itwill appear presently that the connector A functions differentlydepending upon whether it is seized by a local selector or by a tollselector.

The exampled operative condition which will be assumed in relation toconnector A contemplates varied classes of service. For example,referring to Fig. 16, bank position 11 is dead. Bank position 12 refersto an isolated local subscriber's exchange line. Bank positions 13, 14,15 and 16 refer to a group of three lines relating to a singlesubscriber, and moreover, the subscriber has an independent manual, (orautomatic) toil loop. Bank positions 21 and 22 refer to a group of twolocal subscriber's line positions relating to an isolated subscriber'sline. Bank positions 23 and 24 refer to a group of lines relating to asingle subscriber, and moreover, the first line of the group occupyingbank position 23 is an exchange toll loop. Bank positions 25 and 26refer to a group of two local subscribers line positions relating to anisolated subscriber's line.

It will appear, presently, that if a local subscriber (calling through alocaliselector) causes the wipers of connector A to attain bank position12 the connector will'function as a nongroup-selecting connector. Thatis, will seize the line thereof and automatically apply ringing currentto it, if it is not busy, and if it is busy will apply a tone audible tothe calling subscriber, indicative of the condition. If a localsubscriber causes the wipers of connector A to attain bank position 13it will automatically rotate-off as a group-selecting connector,regardless of its busy or idle state, its wipers attaining bank position14, where it will seize the line thereof, if it is not busy, and if itis busy, it will automatically rotate-ofi as a group selectingconnector, its wipers attaining bank position 15, where it will seizethe line thereof if it is not busy, and if it is busy, it willautomaticallyrotate-oif as a group-selecting connector, its wipersattaining bank position 16, where it will seize the line thereof if itis not busy, and if it is busy, it will apply a. tone audible to thecalling subscriber, indicative of the condition. If a local subscribercauses the wipers of connector A to attain bank position 21, it willautomatically rotate-01f as a group-selecting connector, regardless ofits busy or idle state, its wipers attaining bank position 22, where iswill seize the line thereof if it is not busy, and if it is busy, willapply a busy tone audible to the calling subscriber, indicative of thecondition. If a local subscriber causes the wipers of connector A toattain bank position 23, it will auto.- matically rotate-off as agroup-selecting connector,'regardless of its busy or idle state, itswipers attaining bank position 24, where it will seize the line thereofif it is not busy, and if it is busy, will apply a busy tone audible tothe calling '125 subscriber, indicative of the condition. If a localsubscriber causes the wipers of connector A to attain bank position 25it will automatically rotate-ofi as a group-selecting connector,regardless of its busy or idle state, its wipers attaining bank position26, where it will seize the line thereof, if it is not busy, and if itis busy, will apply a busy tone audible to the calling subscriberindicative of the condition.

Assume that it is desired to reach the local line leading from the bankcontacts occupying bank position 15, this line leading to a specifictelephone on the premises of the subscriber or is temporarily connectedto such a telephone, perhaps at night or on a holiday. Upon the callingsubscriber, calling through a local selector, causing the wipers ofconnector A to attain bank position 15 it will seize and ring upon theline thereof if it is idle, and if it is busy, will apply a tone audibleto the calling subscriber indicative of the condition. This is to say,if the line is busy it will not function as a group-selecting connectorand rotate its'wipers into position 16.- Thus, where the wipers of theconnector A primarily attain an interme diate bankposition of a group itwill not thereafter function as a group selecting connector whencontrolled through a local selector. However, it will presently appearthat where the connector is controlled through a toll selector, the tolloperator by sending digit 1 can cause it to thereupon function as agroup-selecting connector. Therefore, upon the operative conditionreferred to with respect to calling through local selectors, it willappear that if the specific intermediate line called is busy analternative line will not be seized, though under the operativecondition of operating the connector A, controlled through a tollselector, the operation of the said connector by way of hunting for analternative line of the group if an intermediate line is called isoptional, at the will of the toll operator.

It will appear, presently, that if a toll operator exchange or remote,calling through a toll selector causes the wipers of connector A toattain bank position 12, the connector A will function as a non-groupselecting connector. That is, it will seize the line thereof preparatoryto the toll operator causing ringing current to be applied to it atwill, if it is not busy, and if it is busy, will apply a tone audible tothe calling operator indicative of the condition. If a toll operatorcauses the wipers of connector A to attain bank position 13, it willseize the line thereof, preparatory to the toll operator causing ringingcurrent to be applied to it at will, if it is not busy, and if it isbusy, will apply a tone audible to the calling operator indicative ofthe condition. Under either condition, that of finding the lineoccupying the bank position 13 (also appearing in bank position 14) idleor busy, a tone will be applied audible to the calling toll operatorthat is of such'specific nature that it is indicative that the calledsubscriber has a toll loop which may be manual or automatic, dependingon the significance of the tone. line occupying bank position 13 isbusy, a composite tone will be audible to the calling toll operatorindicative of the said two conditions, the general nature of thecomposite tone being as hereinbefore referred to. The calling tolloperator at this juncture can either withdraw the switching plug andrelease the connection in the manner as will appear presently andcomplete the call to the called subscriber over his independent tollloop, or the operator can apply ringing current at will to the selectedline after it becomes idle and the connector thereupon automaticallyseizes in the manner as will appear presently. In this connection itwill be remembered that the line seized at bank position 13 is the sameline as appears in bank position 14, therefore, if a busy conditionis'found at bank position 13 as set forth, a busy condition will alsoexist on the line should it have been seized through bank position 14.

Assume now that when the toll operator causes the wipers of connector Ato attain bank position 13, the busy condition alluded to is found. Andfurther, it will be assumed that the toll operator desires to completethe call over one of the subscribers local lines. In order to initiatethe group-selecting operation of connector A the calling toll operatorwill send digit 1, whereupon the wipers of connector A will be advancedto bank position 14, and due to the busy condition that will also befound there, will automatically advance the wipers intobank position 15.If the line leading from bank posi If the tion 15 is idle the connectorwill seize, preparatory to the toll operator applying ringing currentover it at will, and if the line thereof is busy the wipers will beautomatically advanced to bank position 16, where the connector A willseize if the line thereof is idle, preparatory to the toll operatorapplying current'to it at will, or if it is busy, to apply a toneaudible to the toll operator indicative of the condition.

If the line occupying bank position 1615 busy as assumed in theforegoing paragraph, the operator can release the shaft of connector Ato normal position by sending digit 1. If the connector A is released inthe manner provided, the calling toll operator by sending the last twodigits of the called number, can cause it to function as before, or bysending two digits relating to some other bank position, can cause it tobe operated by way'of reaching the line leading to the premises of someother wanted subscriber also accessible to connector A. This feature isparticularly advantageous in that it obviates releasing the entireconnection if a busy line condition is encountered. Where the callemanates from a remote toll switchboard it admits of the line andconnections up to and including the connector being retained interlinkedwhen releasing the connector, and thus saves the time of operators andtoll lines that would necessarily have to be occupied in establishing anew connection up to the connector, were it necessary to release theentire connection.

If the toll operator desires to reach a specific line of the group13-14P15-16, the line leading from the bank contacts occupying bankposition 15 for example, and accordingly sends the proper impulses tocause the wipers of connector A to primarily attain that bank position.If the line is idle, the connector will seize, preparatory to the tolloperator applying ringing current to it at will, and if it is busy atone audible to the toll operator will be applied indicative of thecondition. Under this condition, that of primarily attaining anintermediate bank position of a group, the connector will not beautomatically adapted to function as a group selecting connector.However, upon the operator sending digit 1 following the connectorprimarily attaining the called bank position the connector willthereupon function as a group-selecting connector and seek the firstsucceeding idle line. This functioning will not depend upon the bankposition primarily attained being busy. That is to say, if the operatorafter ringing upon an idle line fails to get a response, sending digit 1will cause the connector to advance its wipers to the first idle line ofthe group and seize it preparatory to the calling toll operator applyingringing current at will. Of course, if the last line of the group isseized or found busy, the connector will not rotate beyond the groupcontaining the called line thereof by reason of the toll operatorsending digit 1 but will, under such condition, restore the shaft tonormal position as has been adverted to hereinbefore.

It will also appear, presently, that if a toll operator (calling througha toll selector) causes wipers of connector A to attain bank position21, said connector A will automatically function as a group-selectingconnector and rotate its wipers into bank position 22. In thisconnection it may be stated that neither a local subscriber nor a tolloperator can cause connector A to stop its wipers resting upon the bankcontacts of bank position 21, for reasons as will appear presently. Ifthe

